本文研究目的是使用Fluent此套裝軟體內的LES之紊流模型及Coupled演算法則模擬不同入流條件下小型三葉水平軸風機的尾流效應，並與實驗結果相互比較。首先，透過本實驗室設計的葉片與實驗設備量測不同入流條件下風機運轉之情形做為模擬所需之條件。而入流條件分為週期性變化之風速和固定風速，其中週期性變化入流為10秒一個週期，速度範圍為4.6～7.6 m s^(-1)，葉片轉速為670～2030rpm。另外，固定風速之下，入流平均速度為6.1 m s^(-1)，葉片轉速為3200rpm，其數據來源為Wu等人(2020)於Energies期刊提供。風洞之截面積為80公分寬 × 80公分高。結果顯示，針對固定風速的模擬分析，其流場模擬至少需要2.5秒以上才會趨於穩定。尾流分析結果皆與實驗結果具有一致性，不管在近尾流區還是遠尾流區，無因次流向速度與實驗值趨勢相同。而紊流強度和動量通量在近尾流區域模擬數值會低於實驗結果，因實驗為侵入性量測、實驗過程葉片受力不均及風洞底面粗糙度之影響，使流場呈現更多能量消耗。頻譜分析也顯示實驗值與模擬數據的分佈斜率皆接近Kolmogorov的斜率 -5/3，證明模擬數據為有效值。針對週期性變化風速的模擬分析，除了將無因次流向速度與實驗值比較外，還有分析不同週期數之模擬結果，其結果表示X/D = 1時，模擬與實驗大致相符，但之後實驗的尾流恢復速度皆大於模擬分析，因實驗風洞呈現變化性入流會有不穩定的情形，使尾流恢復速度加快，以及在風速快速變化之下產生實驗誤差的可能性增加。另外，不同週期數的模擬結果幾乎相同，顯示出模擬對於週期性變化有很好的穩定性。

The purpose of this study is to simulate the wake effect of a small three-blade horizontal axial wind turbine under different inflow conditions by using the turbulence model of LES and Coupled algorithm in Fluent software and compare it with the experimental results. Firstly, use the blades and experimental equipment designed in the laboratory to measure the operation of the wind turbine under different inflow conditions as the required conditions for simulation. The inflow conditions are divided into periodically wind speed and fixed wind speed. The periodical inflow is 10 seconds per cycle, the velocity range is 4.6～7.6 m s^(-1), and the blade speed is 670～2030 rpm. In addition, at a fixed wind speed, the inflow velocity is 6.1 m s^(-1), and the blade speed is 3200 rpm.
The results show that for the simulation analysis of fixed wind velocity, the flow field needs at least 2.5 seconds to stabilize. The non-dimensional flow velocity of wake analysis has the same trend as the experimental value in the near and far wake regions. The spectrum analysis also shows that the distribution slope of the experimental values and the simulated data is close to Kolmogorov's slope -5/3, which proves that the simulated data is effective. For periodic changes in wind speed simulation analysis, the result shows that when X/D = 1, the simulation and the experiment are roughly in agreement. Moreover, the results of different cycles are almost the same, showing that the simulation has good stability to periodic changes.

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